This shared instrumentation grant proposal is for the purchase of a digital, real-time autoradiography system with multiple radiolabel capability. The NIH-funded research projects that require this system are aimed primarily at developing new molecular imaging agents and validating existing radiotracers for the investigation of fundamental biological processes and the assessment of the impact of therapeutic interventions. The system will be located in the Center for Small Animal Imaging (CSAI) alongside systems representing the major in vivo imaging modalities (ultrasound, bioluminescence/fluorescence, X-ray CT, PET, SPECT, MRI and MRS). The CSAI also has a cryo-microtome that will facilitate the preparation of tissue slices for autoradiography. A key benefit of the autoradiography capability to many of the studies will be the opportunity to obtain high-resolution, quantitative data to assist in the interpretation and validation of in vivo imaging metrics. The CSAI functions as a Core Facility for the university and operates as part of the Vanderbilt University Institute of Imaging Science. The autoradiography system will be supported by an experienced group of imaging scientists and a highly qualified support staff. It also will be a key resource for postdoctoral trainees supported by our institutional training program in cancer imaging as well as our other trainees in imaging science.